The results of the two ballots – one on the harmonisation of terms and conditions for maintenance staff who transferred from the private sector the other on a two-year pay offer for 5,000 signal workers and other staff – will be known by 22 May. Strikes could take place shortly after.

But Bennett called for a calm and considered response from workers.

“We would ask all our employees to consider carefully the issues on the table,” he said last night.

“On the one hand, we have a very fair offer that compares very favourably with wage settlements across the country, and on the other there is nothing on the table on which to protest or strike about. We’d ask employees to use their vote to turn away from damaging industrial action.”

RMT general secretary Bob Crow insisted that Network Rail had been using harmonisation talks to try to drive down workers’ conditions, and called the offer “pathetic”.

On the pay dispute, he added: “We told the company quite clearly that the second-year element of their pay offer to operational staff, of [Retail Price Index inflation] plus 0.5%, would not protect our members against costs that are rising way ahead of the official inflation rate.”